Such a switch is e.g. known from the technical journal "Electronic Letters", volume 26, no. 1, pages 4 and 5, (publication date Jan. 4, 1990).
The basic element of a switching matrix shown there in FIG. 3 is a switch per FIG. 1, made of Ti: Li Nb O.sub.3. Such a switch consists of a forked optical waveguide, whose fork fines are flanked by laterally and centrally-located electrodes, of which the central one has an extension that overlaps the narrow fork area. Because of the nonlinear optical characteristics of the Ti: Li Nb O.sub.3, e.g. a dependency of the index of refraction on the strength of the applied electrical field, light that is routed to the switch from the non-branched side can either be guided exclusively into one or the other fork tine by applying preset voltages to the electrodes, or can be distributed to both fork fines at a predetermined ratio.
The light distribution takes place according to the principle of the optical directional coupler, which is described in more detail e.g. in "Applied Physical Letters", volume 27, no. 5, Sep. 1, 1975, page 289 and on.
The waveguide structure forming the optical switch, which consists of optically nonlinear material, must be produced in or on a mechanically stable carrier, e.g. a substrate, which cannot be produced in any desired size. The known switch must therefore be coupled to passive waveguides via other couplers not depicted in FIG. 1, preferably with a fixed adjustment, which serves to supply and guide the light flux to be distributed. If we consider configurations in which several switches are integrated on a single substrate, each switch has four couplers, three of which are used to connect to passive optical waveguides.
If an easily handled optical nonlinear material is to be used instead of Ti: Li Nb O.sub.3, an NLO-polymer is suitable. However, it has a higher attenuation than Li Nb O.sub.3, so that the losses that occur in the couplers and in the waveguide paths made of NLO-polymer significantly determine the total attenuation of the optical switch.